Posting (unmarked) LLM-generated content on public discussion forums is polluting the commons. If I want an LLM's opinion on a topic, I can go get one (or five) for free, instantly. The reason I read the writing of other people is the chance that there's something interesting there, some non-obvious perspective or personal experience that I can't just press a button to access. Acting as a pipeline between LLMs and the public sphere destroys that signal.